Adhesive resin components contained in wood materials and adhesives or synthetic resins mixed into pulps are referred to as “pitch” in papermaking. Pitch particles dispersed in a colloidal state in a pulp slurry aggregate into an enlarged aggregate in water due to their high hydrophobicity. In papermaking, such pitch causes problems such as the formation of a discontinuity or a hole in paper. In order to eliminate pitch to solve such problems, various pitch control agents and methods for suppressing pitch have been examined.
As such a technique, for example, Patent Literature 1 discloses a method for suppressing pitch in a facility including pulp manufacturing equipment for manufacturing pulp from a pulp material by using water. The method includes the step of adding a chelating agent to portions where pulp or an intermediate body thereof is in contact with water in the pulp manufacturing equipment so that a mole ratio (chelating agent/calcium) of the chelating agent to the calcium in the water in the target portions in the pulp manufacturing equipment is one fifth or less. The chelating agent contains one or two or more kinds of an ethylenediaminetetraacetic acid and salts thereof, a diethylenetriaminepentaacetic acid and salts thereof, a triethylenetetraaminehexaacetic acid and salts thereof, and a glycoletherdiaminetetraacetic acid and salts thereof.
In addition, Patent Literature 2 discloses a pitch control agent for papermaking containing, as an active ingredient, a polymer including a constitution unit originating from a specific (meth)acryloyloxy alkyltrialkyl ammonium salt and a constitution unit originating from a specific (meth)acrylic acid or a salt thereof.
Among hydrophobic group-containing copolymers, a copolymer of a hydrophobic group-containing monomer and a carboxylic acid-based monomer or the like is used, for example, as detergent builders. As such a technique, for example, Patent Literature 3 discloses a hydrophobic group-containing copolymer including a structural unit (a) derived from a specific ether linkage-containing monomer (A) and a structural unit (b) derived from a carboxyl group-containing monomer (B), the amount of the structural unit (a) being 1% to 50% by mass and the amount of the structural unit (b) being 50% to 99% by mass based on 100% by mass of the structural units derived from all monomers.